Data are presented on the phase relations in the La2O3-SrO-Ga2O3 system and the effect of B2O3 additions on the structure and morphology of (La,Sr)(Ga,Mg)O3-δ ceramics. The formation of the perovskite phase (La,Sr)GaO3 is shown to proceed through La4SrO7 and La2SrO4 + δ. The unit-cell of (La,Sr)(Ga,Mg)O3-δ is found to vary linearly with Sr + Mg content. The introduction of boron-containing additions reduces the sintering temperature of the ceramics by up to ≃200°C. © 2001 MAIK "Nauka/Interperiodica".